Furnace for burning pulverized fuel



)une 23, 1931. w, R WOOD 1,811,657

FURNACE FOR BURNING PULVERIZED FUEL original Filed Jima 16, 1925 v.f/f YINVENIOR fm 5 ATTORNEYS Patented `lune 23, 1931 UNiTED sTATEs PATENTOFFICE WILFRED R. WOOD, OF LONDON, ENGLAND, ASSIGNOR TO INTERNATIONALCOMBUS- TION ENGINEERING CORPORATION, OF NEW YORK, N. Y., A CORPORATIONOF DELA- WARE FURNACE FOR- .BURNING PULVERIZED' FUEL Application ledTune 16, 1925, Serial No. 37,428, and in Great Britain September 26,1924. Renewed March 13, 1931.

This invention relates to impi'ovements in furnaces for burning finelydivided fuel 1n suspension particularly as regards the manner ofdisposing of asli and refuse. .v

In the burning of pulverized fuel difficulties are encountered becauseof the ash and refuse becoming fused due to high temperatures, whichresults in slag formations of an objectional nature, not to be easilyremoved.

Spaced cooling tubes across the furnace below the zone of combustionhave been provided heretofore for lowering the temperature of the ashparticleswith theresults that the above dilliculties have been greatlyobviated.

I aim to provide an limprovedarrangement of cooling means for overcomingslagging and fusing diiculties in a simple, inexpensive a'nd effectivemanner. p

More specifically stated, it is an object of this invention to providethe combustion chamber of the furnace with a hopper shaped bottom,having surfaces rovided' with tubes thru which a heat absor ing mediumis circulated, whereby the temperature of the ash is lowered belowfusion temperature.

How the foregoing, together with such other objects and advantages asmay hereinafter appear, or are incident to my invention, are realized,is illustrated in preferred form iii the accompanying drawings, whereinFig. 1 is a vertical longitudinal section thru a pulverized fuel burningfurnace for carrying out my invention; and

Fig. 2 is a section taken on the line 2-2 of Fi l.

leferring now more particularly to Fig. l the combustion chamber isindicated by the reference letter A, the lower portion of any suitabletype of boiler b the reference letter B, the burner or fuel eliverymeans at C, and the ash pit at the bottom of the combustion chamber atD.

In the present instance fuel and air are introducedv thru the burner orburners C in a downward direction, and take-s a U-bend in the zone ofcombustion a-nd passes out thru the outlet 5, under control of thedraft. The hot gases and products of combustion in passing thru theoutlet 5 generate steam in the boiler B, tubes of which extend acrossvthe outlet opening. Auxiliary damper controlled inlets 6 are providedat various points in the front wall of the furnace.

The bottom of the furnace or ash pit is of hopper shape, the inclinationof the sides 7 and 8 thereof being greater than the angle of repose ofthe refuse or ash, so that such particles will gravitate tothe bottom ofthe pit as will hereinafter more fully appear.

The inner surfaces 9 and 10 of the ash pit D. and the lower portions ofthe front and rear upright walls are provided with cooling meansextending thereover, such means fin this instance being shown as aplurality of closely spaced tubes 11 thru which cooling fluid,preferably water is caused to flow, such extend from the lower part ofthe ash hopper or pit D upwardly for soine distance adjacent the insidesurfaces of the combustion 'chamber A, thus providing cooled wallsurfaces as well as cooled ash pit surfaces, making it possible todecrease the size of the combustion chamber and/or the boiler proper,besides protecting the upright walls.

I have shown the tubes 11 provided with overlapping fins 18, (see Fig.2), sov that a more or less continuous cooling surface is provided. Itis to be understood, however, that this continuous surface may be formedin 'other ways, as for example, by providing grooved metallic blocksclosely fitting the tubes llso as to conduct heat received by radiationto all parts of the tubes.

It will be seen from the foregoin that the ash and refuse whichgravitate uring the burning of the fuel will lodge on the coolingsurfaces and such surfaces being cool, particles will be cooled and takea granular-like form, with the result that, be-

cause of the angle of inclination, they will gravitate.

The arrangement is particularly useful where vertical firing is employedbecause this form of tiring has a tendency to throw down refuseparticles. In addition the cooling surfaces, because they are subject toradiant heat, evaporate such large quantities of Water as to make itpossible to materially cut down the size of the boiler proper, and togreatly increase the capacity of an vexisting boiler if added thereto.The arrangement is also one which reduces the amount of dead spacerequired in the combustion chamber as the flames may be brought furtherdown than heretofore possible. This means that a. smaller combustionchamber can be utilized, or stated in another way, that more fuel can beburned in a combustion chamber of given size.

The opening 2O at the bottom of the ash it D may be of such dimension asto allow tree passage of the particles of ash and small clinlrer. Anysuitable form of discharge openingsat the lowest part of the incline,however, may be provided.

I have shown a trough Q1 of necessary eX- tent below the opening 2Opreferably containing water for receiving the refuse from whence it maybe removed in any suitable manner, such trough also serving to preventpassage of air in through the opening Q0.

In some instances, it may be desirable to to have the tubes llconstitute superheater tubes, or part superheater tubes and part watercirculation tubes connected into the boiler circulation. lVhensuperheater tubes are used, such tubes are connected to the steam spaceof the boiler.

lei-tain of the advantages herein pointed out are effectively realizedby virtue of the fact that very rapid circulation is obtained thru thecooling tubes.

I claim:

l. In a furnace for burning finely divided fuel in suspension. a boiler,a combustion chamber having substantially upright walls and a slopingbottom portion therebelow, a plurality of closely spaced tubes liningthe sloping bottom portion and extending up wi hin the combustionchamber adjacent an upright Wall thereof, each of the said tubes lyingin a substantially upright plane and having within the furnace andbottom thereof fin members at opposite sides, the fins on one tubebeine' in substantial juxtaposition to the fins on adjacent tubes toform a continuous metallic surface, the said tubes being bent at theirupper ends to extend outthrough a wall of the combust-ion chamber, andmeans connecting said tubes into the circulation of the boiler.

2. In a furnace for burning finely divided fuel in suspension, a boiler,a combustion I chamber having substantially upright walls and a slopingbottom portion therebelow, a plurality of closely spaced exposed tubeslining the sloping bottom portion and extending up Within the combustionchamber adja cent an upright `wall thereof, each of the said tubes lyingin a substantially upright plane and having lin members at the oppositesides thereof, the tins on one tube overlapping the fins of the adjacenttubes, the upper ends of said tubes extending through a wall of thecombustion chamber, and means connecting the said tubes into thecirculation of the boiler.

3. In a. furnace for burning finely divided fuel in suspension, aboiler, a combustion chamber having upright Walls and a sloping bottomfor discharge of refuse, a plurality of closely spaced exposed tubeslining the bottom and disposed at an angle greater than the angle ofrepose of refuse particles and exposed water-tube-wall portions liningat least a substantial part of upright walls adjacent the bottom of thechamber and connected for circulation whereby heat is absorbed insubstantial quantities above the said bottom.

4. In a furnace for burning finely divided fuel .in suspension, aboiler, a combustion chamber having upright Walls and a sloping bottomfor discharge of refuse, a plurality of closely spaced exposed tubeslining the bottom and disposed at an angle greater than the angle ofrepose of refuse particles and exposed water-tube-wall portions liningat least a substantial part of upri ht walls adjacent the bottom of thecham er and connected for circulation whereby heat is absorbed insubstantial quantities above the said bottom, the said tubes and thewater tube wall portions being in series connection.

5. In a nurnace for burning finely divided fuel in suspension, a boiler,a combustion chamber having upright walls and a hopper shaped bottomhaving a centrally disposed discharge: orifice, two sets of closelyspaced exposed tubes lining the sloping sides of the bottoml anddisposed at angles greater than the angle of repose of the refuseparticles, and two exposed water tube-wall portions dining two oppositeupright wall portions adjacent the bottom of the chamber and connectedin series with said tubes, the tubes and the water tube wall portionsbeing connected into the circulation of the. boiler.

In testimony lwhereof, I have hereunto signed my name.

lV. R. IVOGD.

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